Bridge in the Altmhl Valley Essing

Richard J. Dietrich

Subject | Bridges have long been a domain of civil engineers. Since structural and technical problems prevail, architects are at the most asked to help in a creative capacity. And yet bridges are structures that can dominate whole stretches of countryside and, when all's said and done, can also lay claim to being part of town or city planning and of architectural importance. The planning of such structures thus calls for a person who combines to an equal and high degree technical with artistic ability.

A good example of this is the bridge over the Main/Danube Canal near Essing in the Altmiihl Valley. Here the valley of the Altmiihl is of particular beauty. In gentle curves the hills dip towards the valley bottom. At the foot of a castle-crowned bluff on a narrow river bank lies the old town of Essing with its picturesque gables and towers. Here a new bridge had to be built to span the canal and its service roads, the new highway and thus the whole of the valley from one side to the other.

After considering a number of designs the client, building authorities and townsfolk decided in 1978 in favour of the novel multispan design by the architect Richard J. Dietrich. With its undulating outline and seeming weightlessness it harmonized well with its surroundings. The technical difficulties it involved were admittedly considerable. In fact, it was not until 1986, after seven years of planning and development work and with the help of engineering know-how and advanced timber construction technology, that the unusual structure was finally realized.

Based on the age-old principle of the freely suspended rope bridge, a continuous band of glulam beams runs ropeway-like from one massive bridgehead to the other over three trestle-shaped piers. With this computed curve, which results in the load being transmitted to 90% in the form of tensile forces, a slim 600 mm cross-section was possible. A row of beams subject to bending over the 75 m of the main span would have had to be six times as high. For a tensile structure of this shape wood is especially suitable, both statically and - in contrast to pure rope constructions - dynamically, for oscillations caused by the crossing of pedestrians or by the wind are absorbed by the material itself without the need

Location

Altmühltal, 93343 Essing, Germany

Client

Rhein-Main-Donau AG. Munich

Design and Construction Dipl.-lng. Richard J. Dietrich, Architect, Traunstein Project Architect Dipl.-lng. A. Skrabl

Structural Engineer Ingenieurbüro Prof. Dr. H. Brüninghoff and Dipl.-lng. Rampf, Ulm

Building Dynamics Prof. Dr. F. Grundmann, Munich

Timber Construction Huber & Sohn GmbH & Co KG,Regensburg

Date of Completion 1986

Costs

Excluding incidentals and special expenses the bridge cost 3.5 million DM to build (5000 DM per m2 of bridge-way). The development costs for special engineering and material tests and the costs of special structure-stabilising measures were about 350 000 DM.

5 | Intermediate wood trestle supports.

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